FSFO in 11g and max performance mode
Date: Fri, 18 Jan 2013 10:55:19 +0530
Message-ID: <CADrzpjGWf2WTFxSq2kuAwMQpN8ftdXj14Nds1D-8c8DjnzkPvg_at_mail.gmail.com>
The foll. mentioned at
http://docs.oracle.com/cd/B28359_01/server.111/b28295/sofo.htm is a bit confusing:
Either maximum availability mode or maximum performance mode can be used with fast-start failover. Maximum availability mode provides an automatic failover environment guaranteed to lose no data. Maximum performance mode provides an automatic failover environment guaranteed to lose no more than the amount of data (in seconds) specified by the FastStartFailoverLagLimit configuration
property. This property indicates the maximum amount of data loss that is permissible in order for an automatic failover to occur. It is only used when fast-start failover is enabled and the configuration is operating in maximum performance mode.
Once fast-start failover is enabled, the broker will ensure that fast-start
failover is only possible when the configured data loss guarantee can be
upheld. If the configured data loss guarantee cannot be upheld, redo
generation on the primary database will be stalled. To avoid a prolonged
stall, either the observer or target standby database may allow the primary
database to continue redo generation after first recording that a
fast-start failover cannot happen.
I believe the 2nd paragraph is applicable only to 11g Dataguard FSFO in
maximum availability mode and NOT to maximum performance mode. Because in
maximum performance mode, all that will happen is, automatic failover will
not happen (if the standby is lagging behind the primary by an amount of
data loss more than FastStartFailoverLagLimit).
But then, the 2nd paragraph also talks about 'configured data loss' whereas in 1st paragraph it says 'Maximum availability mode provides an automatic failover environment guaranteed to lose no data.' So does it mean that 2nd paragraph applies to both modes meaning even in maximum performance mode, redo generation at primary will be stalled?
Can somebody pls help me understand?
Thanks
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Jan 18 2013 - 06:25:19 CET